How do I transition a patient from warfarin (Coumadin) to enoxaparin (Low Molecular Weight Heparin) and what is the appropriate dosing and monitoring?

Transitioning from Warfarin to Enoxaparin: Dosing and Monitoring Protocol

The recommended approach for transitioning a patient from warfarin to enoxaparin is to discontinue warfarin, start enoxaparin at a therapeutic dose of 1 mg/kg twice daily subcutaneously when INR falls below 2.0, and monitor anti-Xa levels as needed. 1

Initial Transition Protocol

• Discontinue warfarin 5 days before any planned procedure or when transition to LMWH is required 1
• Begin enoxaparin when the INR falls below 2.0 1
• Standard therapeutic dosing for enoxaparin is 1 mg/kg subcutaneously twice daily 1
• For patients weighing ≥40 kg/m², consider a reduced dose of 0.8 mg/kg twice daily 1

Dosage Adjustments Based on Patient Factors

• For patients with renal impairment:
  • Moderate renal impairment (CrCl 30-50 mL/min): Use 0.8 mg/kg twice daily after an initial unadjusted dose of 1 mg/kg 2
  • Severe renal impairment (CrCl <30 mL/min): Use 0.66 mg/kg twice daily after an initial unadjusted dose of 1 mg/kg 2
• For patients with high bleeding risk, consider a half-therapeutic dose regimen of 1 mg/kg once daily 3
• For cancer patients, enoxaparin can be dosed at 1 mg/kg every 12 hours (or 1.5 mg/kg once daily after the first month) 1

Monitoring Protocol

• Anti-Xa activity monitoring is generally not required for most patients on standard doses 1
• Consider monitoring anti-Xa levels in patients with:
  • Severe renal impairment
  • Extreme body weight (very low or very high)
  • Pregnancy
  • Recurrent thrombosis despite treatment 1
• Target anti-Xa level: 0.5-1.2 IU/mL for twice-daily dosing, measured 4 hours after injection 2
• Monitor for signs of bleeding or thrombosis during the transition period 1

Duration of Therapy

• For VTE treatment in cancer patients, continue enoxaparin for at least 6 months 1
• For bridging therapy before procedures:
  • Resume enoxaparin 24-48 hours after the procedure if hemostasis is adequate 1
  • For high bleeding risk procedures, wait 48-72 hours before resuming therapeutic doses 1

Special Considerations

• Enoxaparin is preferred over warfarin for cancer patients with VTE due to lower recurrence rates 1
• Direct oral anticoagulants (DOACs) are now preferred over warfarin for many patients, but enoxaparin remains important for certain populations including those with cancer, pregnancy, or requiring bridging therapy 1
• For patients transitioning back to warfarin, overlap enoxaparin and warfarin for at least 5 days and until INR is therapeutic (≥2.0) for two consecutive days 1, 4

Common Pitfalls to Avoid

• Avoid abrupt discontinuation of warfarin without bridging for patients at high thrombotic risk 1
• Do not reduce enoxaparin dose based solely on minor bleeding without consulting a specialist 1
• Avoid monitoring with aPTT, as this is not appropriate for LMWH therapy 2
• Do not continue the same dose in patients with significant renal impairment, as this can lead to accumulation and bleeding 2